1. Field of the Invention
The present invention relates to a vascular prosthesis, methods of manufacturing such a prosthesis and to a substrate suitable for manufacturing the prosthesis. More particularly, the invention relates to a vascular prosthesis having tissue fragments and/or cells adhered to and captured within the wall of the prosthesis, to methods of manufacturing such a vascular prosthesis and to substrates suitable for manufacturing such vascular prostheses.
2. Description of Prior Art
Various vascular prostheses are known. Some are made of synthetic polymers such as polytetrafluoroethylene or polyester. Others are made of human cord veins, animal blood vessels and of various biological tissues crosslinked with glutaraldehyde as the crosslinking agent. When such vascular prostheses are placed in a mammalian or human body, the inner walls of the prostheses become coated with endothelial cells, which possess antithrombotic properties for preventing blood clotting and deposition of thrombus on the inner walls.
In actual clinical applications, however, coating by the endothelial cells is usually extremely delayed and, in most cases, only the area of the anastomosis of the vascular graft becomes covered with endothelial cells while positions remote from the anastomosis are not covered. Accordingly, thrombus deposits The cells can then separate and be washed away by the blood flow. As a result, this technique has not been clinically applied.
It is an object of the invention to provide a substrate suitable for obtaining vascular prostheses free from the above defects having various tissue fragments and/or cells deposited and captured within the walls of the prosthesis.
It is an additional object of the Invention to provide a vascular prosthesis obtained by depositing and capturing various tissue fragments and/or cells within walls of such a suitable substrate.
It is a further object of the invention to provide a method of manufacturing vascular prostheses having various tissue fragments and/or cells deposited and captured on and within the walls of the prosthesis.
To achieve the above objects, the Invention of the present application relates to a vascular prosthesis where fragments of biological tissues such as vascular tissue, connective tissues, fat tissues and muscular tissues; cells of vascular walls such as vascular endothelial cells, smooth muscle cells or fibroblast cells; and mixtures of biological tissue fragments, mixtures of vascular wall cells or mixtures of biological tissue fragments and vascular wall cells are deposited and captured at least within a wall of the vascular prosthesis substrate. The term "and/or" as used throughout this specification is meant to encompass various combinations.
In order to further achieve the above objects, a manufacturing process is described which comprises the steps of immersing a vascular prosthesis substrate in a disperse solution of fragments of biological tissues such as vascular tissues, connective tissues, fat tissues and/or cells composing vascular walls such as vascular endothelial cells, smooth muscle cells or fibroblast cells, and depositing and capturing the cells and/or tissue fragments within the walls of the prosthesis substrate by providing a pressure differential between the inside and the outside of the prosthesis wall cells or features of biological tissue fragments and vascular wall cells are deposited and captured at least within a wall of the vascular prosthesis substrate. The term "and/or" as used throughout this specification is meant to encompass various combinations.
In order to further achieve the above objects, a manufacturing process is described which comprises the steps of immersing a vascular prosthesis substrate in a disperse solution of fragments of biological tissues such as vascular tissues, connective tissues, fat tissues and/or cells composing vascular walls such as vascular endothelial cells, smooth muscle cells or fibroblast cells, and depositing and capturing the cells and/or tissue fragments within the walls of the prosthesis substrate by providing a pressure differential between the inside and the outside of the prosthesis substrate.
In order to further achieve the above objects, a substrate suitable for manufacturing such a vascular prosthesis is described. The substrate can comprise a porous membrane having pores capable of trapping tissue fragments or cells therein. The substrate can be a laminate structure of such a porous membrane and another porous membrane having pores not large enough to allow the tissue fragments or cells to pass through.
The biological tissue fragments and/or cells comprising the blood vessel described herein are deposited and captured on and within the wall of the prosthesis and can extend from one side to the other side of the wall. This concept differs from the prior art technique of depositing cells only on the inner surface of the vascular prosthesis.
In the present invention, the biological tissue fragments and/or cells are introduced through the mesh structure of the substrate of the vascular prosthesis from outside or inside of the vascular prosthesis and, therefore, they are entangled within the mesh structure of the wall of the vascular prosthesis. Accordingly, in spite of high blood pressure or rapid blood flow, peeling of tissue fragments or cells, or cracks among cells can be avoided and, moreover, unlike a conventional cloth-made vascular prosthesis, the prosthesis of the present invent(on is free from preclotting operations such as treating with blood to form a rigid fibrin layer.
Furthermore, in the present invention, when the patient's (i.e., a mammal including humans) own tissues are used as tissue fragments and vascular wall cells, the procedure represents an autograft and is completely free from rejection by the patient's body, so that a preclotting operation is not needed.